Prior art teaches several types of location tracking systems. Satellite based tracking systems, e.g. Global Positioning System (GPS), are probably the most common location tracking systems. However, their problem is that they are not suitable for indoor location tracking, because GPS signals do not penetrate building walls. For indoors location tracking, prior art teaches systems that utilize a pico network of wireless base stations, and the location of a given person in the coverage area of the pico network is determined on the basis of which wireless base station currently serves a personal communication device of the person. A problem with such systems is that if high resolution is needed for the tracking, numerous base stations have to be disposed throughout the area where the location tracking is to be carried out. This leads to high installation and maintenance costs.